Method and apparatus for the pulse-wise supply of a vaporized liquid reactant

Abstract

Methods and structures provide vaporized reactant from a liquid source to a vapor deposition reactor, such as an atomic layer deposition (ALD) reactor. A storage container holds the bulk of liquid reactant (or solid reactant dissolved in a liquid solvent) outside of the reactor hot zone(s), and so are not subject to decomposition from prolonged exposure to high temperatures. The storage container is in fluid communication with a vaporization chamber within a hot zone of the reactor, such that a high vapor pressure can be maintained within the vaporization chamber. Refilling the storage container outside of the hot zone(s) is simplified, and the bulk of the liquid reactant is not subject to prolonged exposure to destabilizing temperatures. At the same time, the advantages of maintaining a vaporization chamber within a hot zone are maintained. Furthermore, between deposition runs, or periodically when not needed, remaining liquid reactant in the vaporization chamber can be drained back to the storage container or to a separate drain container, where cooler temperatures are maintained.

We claim:  
     
         1 . A system for feeding a low vapor pressure reactant to a reaction chamber, comprising: 
 a storage container at a first temperature T 1 , the storage container containing an amount of liquid reactant;    a vaporization chamber positioned in a hot zone at a second temperature T 2 , higher than T 1 , the vaporization chamber connected with the storage container through a liquid reactant feed line and configured to be partially filled with liquid reactant and to collect vaporized reactant above a surface of the liquid reactant in an upper part of the vaporization chamber; and    a reaction chamber positioned in a hot zone at a third temperature T 3 , wherein T 3  is higher than T 1 , the reaction chamber being connected to the vaporization chamber through a vaporized reactant feed conduit.    
     
     
         2 . The system of  claim 1 , further comprising a drain at one end connected to a bottom part of the vaporization chamber to drain residual reactant after use.  
     
     
         3 . The system of  claim 2 , wherein the drain comprises the liquid reactant feed line in communication with a pump and the storage container.  
     
     
         4 . The system of  claim 2 , wherein the drain comprises a drain conduit communicating at one end with the vaporization chamber and at the other end with a drain container to collect drained reactant.  
     
     
         5 . The system of  claim 4 , further comprising a liquid mass flow measuring device in the drain conduit.  
     
     
         6 . The system of  claim 1 , wherein T 3  is higher than or equal to T 2 .  
     
     
         7 . The system of  claim 1 , wherein the hot zone of the vaporization chamber and the hot zone of the reaction chamber are in intimate contact.  
     
     
         8 . The system of  claim 1 , wherein the hot zone of the vaporization chamber and the hot zone of the reaction chamber are in free thermal communication with each other and thermally insulated from the storage container.  
     
     
         9 . The system of  claim 1 , wherein the hot zone of the vaporization chamber is part of the hot zone of the reaction chamber.  
     
     
         10 . The system of  claim 1 , wherein vaporized reactant is directed from the vaporization chamber to the reaction chamber through an inert gas valving system.  
     
     
         11 . The system of  claim 1 , further comprising a liquid flow control device in the liquid reactant feed conduit.  
     
     
         12 . A method for providing vapor phase reactant from solid or liquid source, comprising: 
 supplying a liquid comprising a precursor from a storage container to a vaporization chamber, the vaporization chamber being at a higher temperature than the storage container;    vaporizing the precursor in the vaporization chamber;    transporting the vaporized precursor to a reaction chamber;    conducting a vapor deposition process using the vaporized precursor in the reaction chamber; and    draining unvaporized liquid from the vaporization chamber after conducting the vapor deposition process without opening the vaporization chamber.    
     
     
         13 . The method of  claim 12 , wherein the liquid is the precursor.  
     
     
         14 . The method of  claim 13 , wherein vaporizing comprises maintaining an unvaporized liquid in the vaporization chamber and generating vaporized precursor above the unvaporized liquid.  
     
     
         15 . The method of  claim 12 , wherein the liquid comprises a solid reactant source dissolved in a solvent.  
     
     
         16 . The method of  claim 15 , wherein vaporizing the precursor comprises vaporizing the solvent and vaporizing the solid reactant source.  
     
     
         17 . The method of  claim 16 , wherein draining comprises providing solvent to the vaporization chamber to dissolve remaining solid reactant source and draining a resultant solution.  
     
     
         18 . The method of  claim 12 , wherein draining comprises returning the unvaporized liquid to the storage container.  
     
     
         19 . The method of  claim 18 , wherein draining further comprises employing a pump.  
     
     
         20 . The method of  12 , wherein draining comprises removing the unvaporized liquid to a dedicated drain container.  
     
     
         21 . The method of  claim 12 , wherein the storage container is kept at a temperature at which the precursor is stable.  
     
     
         22 . The method of  claim 21 , wherein the vaporization chamber is kept at a vaporization temperature below the boiling point of the precursor.  
     
     
         23 . The method of  claim 22 , wherein transporting comprises flowing the vaporized precursor along conduits maintained at or above the vaporization temperature.  
     
     
         24 . The method of  claim 22 , wherein the vaporization chamber is maintained within a first hot zone in intimate contact with a second hot zone accommodating the reaction chamber.  
     
     
         25 . The method of  claim 24 , wherein the first hot zone and the second hot zone share at least some insulating elements.  
     
     
         26 . The method of  claim 22 , wherein the vaporization chamber and the reaction chamber are maintained within a single hot zone.  
     
     
         27 . The method of  claim 22 , wherein transporting comprises supplying pulses of the vaporized precursor to the reaction chamber alternatingly with pulses of at least one other precursor.  
     
     
         28 . The method of  claim 27 , wherein transporting comprises alternatingly stopping and allowing flow of the vaporized precursor from the vaporization chamber to the reaction chamber with an inert gas diffusion barrier.  
     
     
         29 . The method of  claim 28 , wherein alternatingly stopping and allowing flow with an inert gas diffusion barrier comprises controlling valves for an inert gas flow outside of a hot zone accommodating the vaporization chamber.  
     
     
         30 . The method of  claim 12 , wherein the vapor deposition comprises atomic layer deposition.  
     
     
         31 . The method of  claim 12 , wherein draining is conducted at regular intervals between a predetermined number of depositions.  
     
     
         32 . The method of  claim 12 , wherein draining is conducted regularly between deposition runs after a predetermined period of time.  
     
     
         33 . The method of  claim 12 , further comprising periodically refilling the vaporization chamber with liquid from the storage container.  
     
     
         34 . The method of  claim 33 , wherein periodically refilling comprises sensing a surface level of unvaporized liquid in the vaporization chamber has fallen below a predetermined level.